Answer:
1. The partial pressure of Br₂ is 0.118951 atm 2) The value of Kp is 2.843 × 10².
Explanation:
1. The reaction at equilibrium will be:
2NOBr (g) ⇒ 2NO (g) + Br₂ (g)
The partial pressure of PNOBr is 0.363 atm, the partial pressure of NO is 0.421 atm, there is a need to find the partial pressure of Br₂, the value of Kp is 0.160. For the given reaction,
Kp = [PNO]² × [PBr₂] / [PNOBr]²
0.160 = [0.421]² × [PBr₂] / [0.363]²
0.160 = [0.177241 × [PBr₂] / 0.131769
[PBr₂] = 0.131769 × 0.160 / 0.177241
[PBr₂] = 0.118951 atm
The partial pressure of Br₂ is 0.118951 atm.
2) The reaction will be,
2NH₃ ⇔ N2 (g) + 3H₂ (g)
Kp is the equilibrium constant, and its value will be,
Kp = [PN₂] × [PH₂]³ / [PNH₃]² ------------------(i)
Considering the reactants in terms of molarity will be,
Kp = [N2] × [H₂]³ / [NH₃]²
Here, [N2] = 0.297 / 16.6 = 0.017892 M
[H₂] = 0.320/16.6 = 0.019277 M
[NH₃] = 3.53 × 10⁻⁴ / 16.6 = 2.12651 × 10⁻⁵ M
Now putting the values in equation (i) we get,
Kp = [0.017892] × [7.16399 × 10⁻⁶] / [4.52204 × 10⁻¹⁰]
Kp = 0.128167 × 10⁻⁶ / 4.52204 × 10⁻¹⁰
Kp = 2.8343 × 10²
Hence, the equilibrium constant is 2.8343 × 10²
An endothermic reaction is one that:
A. produces light
B. produces gas
C. involves no temperature change
D. absorbs heat
cines exam
Answer:
D. absorbs heat
Explanation:
Examples of endothermic reactions ---
1.Melting ice cubes.
2.Melting solid salts.
3.Evaporating liquid water.
1. What does the atomic number of an element represent?
O A the number of neutrons
B the number of electrons
C the number of orbitals
D the number of protons
Answer:
D The number of protons
The specific spatial arrangement of amino acid residues that are close to each other in the polypeptide chain is called______the structure of a protein.
a. primary.
b. secondary.
c. tertiary.
d. quaternary .
Answer:
c. tertiary.
Explanation:
In this case, we can review the definition of each level of structuration in the proteins:
Primary structure
In the primary structure, the amino acids are linked by peptide bonds. That is, the order of the amino acids is the criterion that defines this type of structure.
Secondary structure
In the secondary structure, we have to look at the way in which the protein is folded. The options are:
-) Beta-laminar: A structure in which the protein has a planar shape.
-) Alpha-helix: A structure in which the protein has a cross-strand form.
Tertiary structure
In the tertiary structure, the R groups that the amino acids have in the primary structure can generate interactions with each other. Interactions such as hydrogen bridges, dipole-dipole, hydrophobic interactions. This makes the protein have a very specific three-dimensional structure, on which its function depends.
Quaternary structure
In the quaternary structure, several subunits may be attached, or there may be prostatic groups (metals that can help to attach various protein units).
With all these in mind, the deffinition that fits with the description in the question is the tertiary structure.
I hope it helps!
The specific spatial arrangement of amino acid residues that are close to each other in the polypeptide chain is called the tertiary structure of a protein.
What is Protein?Protein structure is three dimensional in shape, where the atoms are arranged in amino acid chain. The chain is polypeptide containing many amino acid sequences.
The tertiary structure have a single polypeptide chain which is called the backbone.
Therefore, the specific spatial arrangement of amino acid residues that are close to each other in the polypeptide chain is called the tertiary structure of a protein.
Learn more on protein structure here,
https://brainly.com/question/17338734
During a titration, the solution with the unknown concentration is called the _____.
Answer:
Analyte.
Explanation:
Hello,
In this case, in a titration, an analyte is known as the the substance whose quantity or concentration is to be carefully determined (initially unknown) by using a titrant with a controlled volume and an accurately-known concentration which is also called a standard solution.
You can verify this by considering the attached picture.
Regards.
A C≡C triple bond contains-
A) 3 σ bonds
B) 2 σ bonds and one π bond
C) one σ bond and 2 π bonds
D) three π bonds
E) one-and-a-half σ bonds and one-and-a-half π bonds
Answer:
i think its D but im not really good with this calls tho
Substances that are composed of a network of atoms held together by covalent bonds are called
O A. ionic lattices
B. giant covalent structures
C. allotropes
D. diatomic networks
Answer:
giant covalent structures
Explanation:
Covalent solids are made up of atoms joined to one another by covalent bonds to form a giant lattice. The covalent bonds are very strong, this makes the giant covalent solids to be hard and possess high melting points. Covalent solids are nonconductors of electricity due to the absence of free electrons in the structure.
Diamond, graphite and boron nitride are all examples of giant covalent structures.
The purpose of the best-fit line on an experimental scatterplot is to:_______.
a. The best-fit line allows us to predict behavior between measured data using its slope.
b. Ignore data points that don't fit the line.
c. Determine individual slopes between each set of data points
Answer: a. The best-fit line allows us to predict behavior between measured data using its slope.
Explanation:
A line of best fit is drawn through a scatter-plot to determine the direction of an relation between two quantities.
The line of best fit can be used to make prediction for the dependent variables.
Hence, the purpose of the best-fit line on an experimental scatter-plot is to predict behavior between measured data using its slope.
Hence, the correct option is "a."
Which acid could not be prepared by treating a Grignard reagent with CO2?
a. p-methylbenzoic acid.
b. cyclopentane carboxylic acid.
c. 4-oxopentanoic acid.
d. 3-methylbutanoic acid.
Answer:
4-oxopentanoic acid.
Explanation:
In this case, we must remember that the Grignard reaction is a reaction in which carbanions are produced. Carboanions have the ability to react with CO2 to generate a new C-C bond and a carboxylate ion. Finally, the acid medium will protonate the carboxylate to produce the carboxylic acid group.
The molecules that can follow the mechanism described above are the molecules: p-methylbenzoic acid, cyclopentane carboxylic acid and 3-methylbutanoic acid. (See figure 1)
In the case of 4-oxopentanoic acid, the possible carbanion will attack the carbonyl group to generate a cyclic structure and an alcohol group (1-methylcyclopropan-1-ol). Therefore, this molecule cannot be produced by this reaction. (See figure 2)
9.
The main difference between the salt in the Dead
Sea and salt in the school lab is that
A salt in the Dead Sea is saltier.
B salt in the Dead Sea is iodized while that
of the lab is uniodized.
C salt in the Dead Sea is sodium chloride while
that of the lab has its hydrogen replaced.
D salt in the Dead Sea is sodium chloride
while salt in the lab is either soluble or
insoluble in water.
Answer:
salt in the Dead Sea is sodium chloride
while salt in the lab is either soluble or
insoluble in water.
Explanation:
The term 'salt' in the school laboratory does not always refer to sodium chloride. It is a generic term used for many substances especially those substances formed by neutralization reaction.
There are many salts that are used in the laboratory. Some of these salts are soluble in water while some are not soluble in water.
Salt in the dead sea always refers to sodium chloride, hence, salt in the dead sea is different from salt in the school laboratory.
Suppose you wanted to study the relationship between high
school graduation rate and crime. What might your hypothesis be?
What would be the independent variable in your study? The
dependent variable? What existing data could you examine to
support your hypothesis?
Answer:
Hypothesis: High school graduation rate does not have an effect on the rate of crime in the society
Independent variable: Rate of high school graduation
Dependent variable: crime
Existing data: Crime data/reports (for the duration of interest) from different (randomized) police stations and the High school graduation rate data/information (for the same duration of interest) from the schools in the same jurisdictions as the police stations.
Explanation:
1) Before conducting an experiment, a hypothesis has to be put forward. This hypothesis is then proven or unproven by the outcome of the experiment. One of the best ways of proposing a hypothesis is the use of null hypothesis, which suggests that there is no significant difference or "connection" between two variables. Here, the null hypothesis can be "High school graduation rate does not have an effect on the rate of crime in the society"
2) An independent variable is a variable whose variation is not determined or thought to be determined by the change(s) in the other variable. Here, high school graduation rate is not determined or thought to be determined by the other variable.
3) A dependent variable is a variable whose variation is predicted to be as a result of the change(s) in the other variable. Here, the rate of crime is predicted to be as a result of the high school graduation rate
4) Existing/available data that can be used to examine the hypothesis proposed earlier can be obtained from the crime data/reports (for the duration of interest) from different (randomized) police stations and the High school graduation rate data/information (for the same duration of interest) from the schools in the same jurisdictions as the police stations.
which of the following molexules would you predict to be most polar? i. co2 ii. cf4 iii. both have the same molecular polarity why?
Answer:
iii. both have the same molecular polarity
Explanation:
Both CF4 and CO2 are nonpolar molecules.
CF4 is a tetrahedral molecule, the compound is highly symmetrical hence the individual dipole moments due to the four C-F bonds cancel out thereby making the molecule to be nonpolar.
Similarly, the direction of the two dipoles in CO2 cancel out since they are directed in opposite directions making the molecule nonpolar.
QUICK WILL MARK BRAINLIEST!!
Match each of the unknown ions to its appropriate description.
A− A) A nonmetal that gained one electron
B+ B) A metal that lost one electron
C2− C) A metal that lost two electrons
D2+ D) A nonmetal that gained two electrons
Answer:
Explanation:
1.A-
2.B+
3.D2+
4.C2-
Which of the following is true about the scientific method?
a
Each step is related to the others.
b
It is an iterative process.
c
All of the answers are correct.
d
It is a step-by-step process.
e
It involves a logical flow.
Answer:
It is a step by step process
Explanation:
You cannot do the experiment and lab report without following the steps
Hope this is correct and helpful
HAVE A GOOD DAY!
Erica is bisecting an angle as shown. Which of the following should be her next step
Answer:
She should bisect from point M and then draw a line from the point where the arcs from M and N meet to point O
At a given temperature, an unknown gas takes 10.0 minutes to travel the distance helium gas travels in 1.66 minutes. What is the approximate molar mass of the unknown gas
Answer:
The molar mass of the unknown is approximate 145g/mol
Explanation:
We can relate the speed of effusion of gases with the molar mass of the 2 compounds using Graham´s law:
[tex]\frac{v_a}{v_b} =\sqrt{ \frac{m_b}{m_a} }[/tex]
Where V is speed of the gas and m molar mass of a and b gases.
Molar mass of helium is 4g/mol. As the distance of the gases is the same, we can replace the speed of effusion with the time the gas takes to travel the distance. The equation will be:
[tex]\frac{t_b}{t_a} =\sqrt{ \frac{m_b}{m_a} }[/tex]
Replacing:
[tex]\frac{10.0min}{1.66} =\sqrt{ \frac{m_b}{4g/mol} }\\6.024 = \sqrt{ \frac{m_b}{4g/mol} }\\36.29 = \frac{m_b}{4g/mol}\\145 g/mol =m_b[/tex]
The molar mass of the unknown is approximate 145g/molWhich of the following affects cell potential?
a. the standard cell potential value
b. the electronegativity of the elements in the electrodes
c. the volume of the solutions
d. all of the above
Answer:
the standard cell potential value
Explanation:
For every cell, we can calculate its standard electrode potential from the table of standard electrode potentials listed in many textbooks.
However, from Nernst's equation;
Ecell= E°cell - 0.0592/n log Q
Hence the standard cell potential (E°cell) affects the value of the calculated cell potential Ecell from Nernst's equation as stated above.
If the components of a solution are in the same state, which one is the solvent?
Answer:
Usually, the substance present in the greatest amount is considered the solvent.
who discovered copper
Explanation:
The exact person is unkown cooper has been around for ages since 9000 BC in the Middle East are the earliest discoveries
Although various copper tools and decorative items dating back as early as 9000 BCE have been discovered, archaeological evidence suggests that it was the early Mesopotamians who, around 5000 to 6000 years ago, were the first to fully harness the ability to extract and work with copper
What is the answer with the correct significant figures to the addition problem 1.2773 + 4.29
Answer:5.5673
Explanation: I searched it up for you
g Which ONE of the following ionic compounds is insoluble in water? A) MgCO3 B) Li2CO3 C) NH4Br D) K3PO4 E) Pb(NO3)2
Answer:
A) MgCO₃ is insoluble
Explanation:
Based on the rules of solubility:
All nitrates are soluble. That means Pb(NO₃)₂ is soluble.
All ammonium ions are soluble. NH₄Br is soluble.
All phosphate are insoluble except when combined with group I ions (Li, Na, K...) K₃PO₄ is soluble.
Also, all carbonates are insoluble except when combined with group I ions. That means Li₂CO₃ is soluble and:
A) MgCO₃ is insolubleSpecify whether each compound is soluble in hexane.Classify the appropriate items to their respective category.
a. hydrogen chloride (HC)
b. hydrogen sulfide (H2S)
c. water (H2O)
d. propane (CH3CH2CHs)
1. Soluble in hexane
2. Insoluble in hexane
Answer:
hydrogen chloride (HC)- insoluble in hexane
hydrogen sulfide (H2S)- insoluble in hexane
water (H2O)- insoluble in hexane
propane (CH3CH2CH3)- soluble in hexane
Explanation:
Generally, it is a principle in chemistry that polar solvents dissolve polar substances while nonpolar solvents dissolve nonpolar substances.
This is because, dissolution of a substance in another substance depends on the kind of intermolecular interaction that is possible between the two substances. Hence, ionic substance dissolve in polar solvents due to dipole interactions and nonpolar substances dissolve in nonpolar solvents due to Vanderwaals interaction between the solute and solvent.
Hydrogen chloride, hydrogen sulphide and water are ionic substances hence they can not dissolve in hexane which is a nonpolar substance. However, propane is a nonpolar solvent hence it dissolves in hexane.
Answer: butane (CH3CH2CH2CH3) soluble
hydrogen chloride ( HCl) insoluble
hydrogen sulfide (H_2S) insoluble
water (H_2O) insoluble
Hydrophobic interactions help to stabilize the ________ structure(s) of a protein.
a. primary
b. secondary
c. secondary and tertiary
d. tertiary and quaternary
e. secondary and quaternary
Answer:
d. tertiary and quaternary
Explanation:
Form or shape of protein can be understood by its structure. The structure of protein encompasses four levels of protein :
Primary (Simplest layer of amino acids in polypeptide chain), Secondary (Atom - Backbone folding structure within polypeptide),Tertiary (R groups of amino acids), Quaternary (multiple polypeptide chain subunits).Hydrophobic Interactions refers to amino acids with non polar r group structure together on inside of protein, which leaves Hydrophobic amino acids outside to interact with surrounding water molecules.
These help to stabilise : D) Tertiary & Quaternary protein structures.
a chemist encounters an unknown metal. They drop the metal into a graduated cylinder containing water, and find the volume change is 3.2 mL. If the metal weighs 1.5g, what is the density in g/mL of the metal?
The density of metal will be "0.469 g/mL".
The given values in the question are:
Mass of metal = 1.5 gVolume of metal or Volume change = 3.2 mLNow,
The density of metal will be:
→ [tex]Density = \frac{Mass}{Volume}[/tex]
By substituting the given values, we get
→ [tex]= \frac{1.5}{3.2}[/tex]
→ [tex]=0.469 \ g/mL[/tex]
Thus the above is the appropriate answer.
Learn more about volume of metal here:
https://brainly.com/question/17928778
The density of the metal is 0.47 g/mL
The density of an object is defined as the mass of the object per unit volume of the object.
Density = mass / volumeWith the above formula, we can obtain the density of the metal. This is illustrated below:
Volume of metal = change in volume of water = 3.2 mL
Mass of metal = 1.5 g
Density of metal =?Density = mass / volume
Density = 1.5 / 3.2
Density of metal = 0.47 g/mLTherefore, the density of the metal is 0.47 g/mL
Learn more: https://brainly.com/question/24472494
What information about a chemical solution can be inferred from knowing its pH value?
Answer:
See the answer below
Explanation:
The information than can be inferred from knowing the pH value of a chemical solution is the hydrogen or hydroxyl ion concentration of the solution.
The pH of a solution is the degree of acidity or alkalinity of the solution. Mathematically, the pH of a solution is expressed as:
pH = [tex]-log_{10}[H^+][/tex] where [tex][H^+][/tex] = hydrogen ion concentration.
Also,
pH = 14 - pOH, where pOH = [tex]-log_{10}[OH^-][/tex]
The more the [tex][H^+][/tex] of a solution, the lower the pH, and the more the [tex][OH^-][/tex] of a solution the higher the pH. The pH value ranges from 0 - 14 with 7 being a neutral pH.
Answer:
Explanation:
The hydrogen or hydroxyl ion concentration of the solution could be inferred from knowing its pH value.
While in Europe, if you drive 109 km per day, how much money would you spend on gas in one week if gas costs 1.10 euros per liter and your car's gas mileage is 22.0 mi/gal ? Assume that 1euro=1.26dollars.
Answer:
113.12 dollars
Explanation:
From the question we are told that you drive 109km/day and your gas milage = 22miles/gallon
Step 1
We convert 109km to miles
1 km = 0.6214 miles
109km =
109km × 0.6214miles/ 1 km
= 67.7326miles
Step 2
Since the gas mileage = 22miles per gallons, we calculated how many gallons of fuel you used in a day
22 miles = 1 gallon
67.7326 miles = x gallon
Cross Multiply
x gallon × 22 miles = 67.7326 × 1 gallon
x gallons = 67.7326 miles × 1 gallon/22 miles
x gallons = 3.0787545455 gallons
Approximately = 3.08 gallons of gas
Hence, in a day you use 3.08 gallons of gas.
Step 3
We are told that has cost 1.10 euros/ liter
Hence, we convert the amount of gas you used in gallons to liters
1 gallon = 3.785 liters
3.08 gallons = y liters
1 gallon × y liters = 3.08 gallons × 3.785 liters
y liters = 3.08 × 3.785/1
y = 11.6578 liters.
So in a day you use 11.6578 liters of gas.
Step 4
Assume that 1euro=1.26dollars.
We are also told that has = 1.10 euros per liters
We convert the amount in Euros to dollars
1 euro = 1.26 dollars
1.10 euros =
1.10 × 1.26
= 1.386 dollars
Hence gas costs 1.386 dollars per liter
Step 5
Since : 1 liter of gas = 1.386 dollars
11.6578 liters of gas =
= 11.6578 liters × 1.386 dollars/ 1 liter
= 16.1577108 dollars
Therefore, in 1 day, you spend approximately = 16.16 dollars on gas
Step 6
The final step:
We are asked to calculate how much you spent on gas in 1 week
1 week = 7 days
Therefore, if
In 1 day you spend = 16.16 dollars on gas
7 days =
= 7 × 16.16 dollars
= 113.12 dollars
Therefore, the amount money you would spend on gas in one week = 113.12 dollars.
59.23
An atom contains one proton, one electron, and one neutron. Which two particles are most similar in mass?
O the neutron and the electron
O the proton and the electron
the proton and the neutron
O the neutron and the atom
Answer:
the proton and the neutron
Explanation:
mass of The proton is approximately 1.6726 × 10^-27 Kg
mass of the electron is approximately 9.109 × 10^-31 Kg
mass of the neutron is approximately 1.6749 × 10^-27 Kg
Here we see that mass of proton and neutron is approximately similar.
_____________________________________________
Lets see what is the mass of these particle IN atm unit
mass of these particles can also be described in form of amu(atomic mass unit)
1 atm is the mass defined as 1/12 th of mass of the carbon-12(c-12) atom.
In terms of unit atm
mass of proton = 1 amu
mass of electron = 5.45 × 10−4 amu
mass of neutron = 1 amu
hence we can say that mass of proton = mass of neutron.
mass of atom is sum of mass of all the neutron and proton in the atom.
Hence, mass of neturon and atom cannot be equal.
This makes option four the neutron and the atom , the wrong choice.
correct answer is the proton and the neutron
therefore, An atom contains one proton , one electron and one neutron then, mass of proton is similar in mass of neutron.
Answer:
proton and neutron
Explanation:
Choose the best answer below. If an equal number of moles of lactic acid, HC3H5O3, and potassium hydroxide, KOH, are added to water, is the resulting solution acidic, basic, or neutral? The Ka of lactic acid is 1.4 x10-5.
Answer:
Solution is basic.
Explanation:
When you add the same moles to a weak acid and strong base, you produce a neutralization reaction and a salt. For this case:
CH₃CHOHCOOH + KOH → KCH₃CHOHCOO + H₂O
If we work in a titration, this is the equivalence point where:
moles of base = moles of acid
For this reaction we are only having lactates ions on solution. All the moles from the lactic acid and the hydroxide will be neutralized to make water. As both numbers are the same, the number is the moles of the formed lactate.
If we think the equilibrium equation for lactate, we have:
CH₃CHOHCOO⁻ + H₂O ⇄ CH₃CHOHCOOH + OH⁻
In conclussion, the solution is basic, because we give OH⁻ to medium.
Notice, that in a titratrion of a weak acid and a strong base, the pH at the equivalence point is always basic.
The element carbon would be expected to form covalent bond(s) in order to obey the octet rule. Use the octet rule to predict the formula of the compound that would form between carbon and bromine, if the molecule contains only one carbon atom and only single bonds are formed. Formula:
Answer and Explanation:
The octet rue depicts the overall trend of chemical bonding in which atoms of an elements would seek to attain stability by filling out their valence shell with eight (8) electrons, giving it the same electronic configuration as a noble gas (specifically Argon).
Hence Carbon with 4 valence electrons (2, 4 electronic configuration) would take on four bromine atoms with 7 valence electrons (2, 8, 4 electronic configuration) each, giving each Br atom the single electron it needs to achieve octet stability.
Carbon tetrabromide
Chemical formula: [tex]CBr_{4}[/tex]
I hope this is a clear explanation
How many asymmetric centers are present in the open chain form of the aldohexose D-(-)-gulose?
A) 0
B) 1
C) 2
D) 4
E) 5
Answer:
D) 4
Explanation:
If we want to find the asymmetric centers, we must first remember that in an asymmetric center, in the carbon, we will have 4 different types of groups bonded to it.
Therefore we must look for carbons that have 4 different groups. With this in mind, we can look at each carbon.
Carbon 1
In this carbon, we have two bonds with the oxygen, therefore, we dont have 4 different groups. So, this is not an asymmetric center.
Carbon 2
In this carbon, we have an "OH" in the top, an hydrogen in the bottom a carbonyl group in the right, and a CHOH in the left. We have 4 different groups. So, this is an asymmetric center.
Carbon 3
In this carbon, we have an "OH" at the bottom, an hydrogen in the top, a CHOH group in the right (that is bonded to a carbonyl group), and a CHOH in the left. We have 4 different groups. So, this is an asymmetric center.
Carbon 4
In this carbon, we have an "OH" at the top, an hydrogen in the bottom a CHOH group in the right (that is bonded to a CHOH group), and a CHOH in the left. We have 4 different groups. So, this is an asymmetric center.
Carbon 5
In this carbon, we have an "OH" at the bottom, an hydrogen in the top, a CHOH group in the right (that is bonded to a CHOH), and a CH2OH in the left. We have 4 different groups. So, this is an asymmetric center.
Carbon 6
In this carbon, we have two bonds with hydrogens, therefore, we dont have 4 different groups. So, this is not an asymmetric center.
See figure 1
I hope it helps!
What is the rate constant of a first-order reaction when 20.0% of a reactant remains after 73.5 s?
Answer:
Half-lives of first order reactions
Explanation:
Notice the the half-life is independent of initial concentration. This is not the case with other reaction orders. The half-life of a first-order reaction was found to be 10 min at a certain temperature. hope this helps you :)
0.0453 sec⁻¹ the rate constant of a first-order reaction when 20.0% of a reactant remains after 73.5 s.
What is rate constant?The constant is indeed a proportional factor in chemical kinetics' rate equation that connects reactant molar concentration to reaction rate. It is additionally known as the pre - exponential factor or reaction rate factor and is represented by the symbol k in an equation.
The constant, k, is indeed a constant of proportionality that illustrates the connection between reactant molar concentration and reaction rate. Using the molar quantities of the reagents and the sequence of reaction, the constant may be determined experimentally. It may also be computed using the Following equations.
t1/2 = 0.693/k
Fraction remaining = 0.5n
n = number of half lives
0.20 = 0.5n
log 0.20 = n log 0.5
n = 2.32
2.32 half lives = 35.5 sec
1 half life = 15.3 sec
15.3 sec = 0.693/k
k = 0.0453 sec-1
Therefore, 0.0453 sec⁻¹ the rate constant of a first-order reaction when 20.0% of a reactant remains after 73.5 s.
To know more about rate constant, here:
https://brainly.com/question/14977272
#SPJ6